How to select entered parameter for report?

Question

I developed a report in SSRS 2008R2 with several parameters. But now when the use selects the Supervisor from this query, it automatically changes to a different supervisor!
Select Distinct
Null As [supervisor_id],
'-All-' As [supervisor_name],
0 as sort
UNION ALL
select distinct
supervisor_id,
staff_name as [supervisor_name],
1 as sort
from staff_view v WITH (NOLOCK)
where staff_id not in ('07BBA230-CA6E-402E-AEAF-FF1CB48AA41A','6394C3A3-5402-4578-BBF1-31FFCDD4EB90')
Order By sort, [supervisor_name]
In my report I have a SupervisorID parameter which uses supervisor_id as the value and supervisor_name as the label. (This is the Text datatype).
I also tried running this as a text query instead of store proc, but this exhibited the same behavior. I also broke down this view into the source tables with the same behavior:
select distinct
supervisor_id,
[supervisor_name] = evolv_cs.dbo.FormatName(people_rv.last_name,people_rv.first_name,people_rv.middle_name) +
Case When IsNull(staff_rv.end_date, '12/31/2100') < GetDate() Then
' (Ended: ' + Convert(Varchar(10), staff_rv.end_date,101) + ')'
Else '' End,
1 as sort
FROM
staff_rv with (nolock)
INNER JOIN people_rv with (nolock) ON staff_rv.people_id = people_rv.people_id
INNER JOIN agency_rv with (nolock) ON staff_rv.agency_id = agency_rv.agency_id
where supervisor_id is not null and
staff_id not in ('07BBA230-CA6E-402E-AEAF-FF1CB48AA41A','6394C3A3-5402-4578-BBF1-31FFCDD4EB90')
Order By sort, [supervisor_name]
I'm not sure what else to try?
Also, the code for FormatName is:
ALTER FUNCTION [dbo].[FormatName](@last [nvarchar](4000), @first [nvarchar](4000), @middle [nvarchar](4000))RETURNS [nvarchar](100) WITH EXECUTE AS CALLERAS EXTERNAL NAME [EvolvSQLCLR].[UserDefinedFunctions].[FormatName]
Ryan D

Answer 1

Hi ironryan,
Thank you for your question.  
I am trying to involve someone more familiar with this topic for a further look at this issue. Sometime delay might be expected from the job transferring. Your patience is greatly appreciated.  
Thank you for your understanding and support. 
Best Regards,
Simon Hou